The invention relates to an adjustable self-clamping loop of a strap composed of a pair of rings superposed according to two parallel planes, and presenting rectangular frames of different sizes, the larger first ring comprising a rectangular first opening located under a rectangular second opening arranged in the smaller second ring, in such a way as to define a transverse slot for passage of the strap, the slot being arranged between one of the external edges of the second ring and the corresponding large side of the first opening of the first ring, the loop being either in a locked position of the strap in the slot following application of a clamping force or in an unlocked position due to a voluntary unlocking action causing sliding of the second ring and an increase of the passage zone in the slot after a rocking movement of the loop.
In this first type of state-of-the-art attachment loops of the kind referred to, the rocking movement by voluntary unlocking action was appreciably hampered by the relative movement of the second ring. Unlocking of the loop then requires a great force to overcome the self-clamping effect of the strap.
A second type of self-clamping loop comprises a single rectangular ring, and a cross-piece movable in translation in the central opening. The opposite ends of the cross-piece cooperate with guiding means provided on two parallel opposite sides of the ring. The structure and manufacture of such an attachment loop are complicated.